Television



March 24, 1931. R, DAV|$ 1,797,259

TELEVI SI ON Filed June 23, 1928 INVENTOR Robert Llflzwz's.

ATT'ORNEY Patented Mar. 24,: 1931 nrncrnrda nnnurncmunme GOMPANYW'VA conronn'rron or rENNsrfLvAnIA TELEvI'sioN I I 7 V I f Application filed June '23, 1 My invention :relates'to television systems, a

,erly, butw11l-vb e seeniaseither too high or too low lntlieviewing lens, depending on the ,directionof rotation of the diskwith respect,

and more i especially to systems of the type wherein theviewto be'transmitted is'analyzed'at: the sending station by a mechanieal- =ly actuated scanning device, and at the receiving station,is reproduced through the agency of a similar device which is actuated in'syn- "chronism with the device at'the'sending station.

Although the broad principle underlying ny'invention is applicable to a widevariety of television systems, it is particularly use- 'ful in connection] with systems wherein the scanning devicestake the form of revoluble disks, each disk being provided with a spirally disposed series of axial openings extending therethrough. 1 I I v At the sending station, a scanning disk of I the type described is interposed between source of light and'the object, a view of which is tohe transmitted and, by being revolved at a'high rate of speed, causes a spot of in! tense light to traverse every portion'of the object.v (The lightrefiected from the object falls ona photo-electric cell, or a plurality .of cells, thus controlling a current which is either transmitted direct'to the receiving station or isutilized toamodul'atej the output of.

a radio-transmitter,' The British patent .to Baird,"269,6.58, exemplifies atelevisionitransthelight-source anda viewing lens and, when it is" revolved in step with the transmitting dish-causes the eye of the observer'to'receive substantially the same visual impressioii as would be, received from the actual I object. L

Inorder that a correct visual impression shall be received bythe observer, it is essen- -tial that the'two disks shall revolve, at the same angular velocity and that they shall be in exact step. Ifthereceiving disk differs in angular relationi'to the sending disk the.

1928.? swam. 287,823. w

ums. mm, or r'rr'rsm nen, mmsyrmfum, *Assisivon'ro vvnsmnsnousn 1 received picture will not be framed propto the spiral series of openings.

It has previously beenproposedto framei the received picture by permitting the motor drivingthe receiving diskto drop momentarily. out of'synchronism and slip poles? until-the picture, appears to be, about right,

and a differential arrangement for a'ccomplishing'the same vresult isldisclosedin the patent to .ltamsey, 1,602,121, Neither method has given entire satisfaction, however,

' since both jot-them involve what might be described as trial-and-error adjustment, a It 1s, accord1ngly, an object of my inven- 7 tion to provide means for framing thereceived p cture in atelevision system that shall "be positivein action and simple to manipulate. s

Another object of my invention is topro vide means for framing the received picture in a television system that shall be independent of scanning device.

Another ob'ect of my invention is to p'ro vide," ina television system, meansi for, fframing there ceived picture that shall'not require trial-and error adjustment.

In the specific modification of my invention that has been chosen asillustrative of the principle thereof, the scanning devices at the receiving station takes the form of; a revolu'b le disk provided with a series of openings ar'-- ,the speedof revolution of the;

ranged along a spiraloftwo revolutions, such as 1s llustrated in the aforementioned Ramsey patent; The variable light "source, the

viewing-frame, and the viewing lens, which elements are hereinafter, designated the.

viewing-assembly howevenare not fixedin pos tion relative to the scanning disk, but are mounted for adjustment radially thereof by ning purposes, and may thus frame e re; l

ceived view in a simple and positive manner means of ;a rack and pinionQ The observer,

thereforefby adjusting the position of theg95 ,bodinient, taken" with the accompanying. drawing, in which: I

ganization and its method of operation, to-' .gether with further objects and advantages thereof, will best be understood byreference to the following description of a specific'em- Figure 1 is a view, in elevation, of a telebodiment of my invention, and

F 2 is a sectional view, taken along a line corresponding to the line II'II of Fig. 1.

The apparatus illustratedin the drawings comprises a disk 1 provided'with a large number of scanning-openings 2 disposed in a spiral having a plurality of convolutions.

' The disk is preferably designed to rotate in geared thereto. 7

a vertical plane, being either mounted directly'on the shaft of a constant-speed'motor or A viewing-assembly, comprising a variable light source 4, preferably a glow-lamp, a viewing or framing aperture 5, and an en: larging lens 6, is so disposed with respect to the disk that light from the glow-lamp is visible to an observer through only one of the scanning openings 2 at a tim V The glow-lamp, is a preferred modification of my'in'vention, comprises a plurality of flat electrodes 20 and 21, which are mounted in a bulb 22 containing neongas under very reduced pressure.

The electrodes are spaced apart a distance less than the mean free path of the gas molecules and, consequently, the discharge between them necessarily spreads out around the edges and takes place between the surfaces which are not closely adjacent;

"The specific type of glow lamp employed forms no part of my invention, it being perfectly feasible to replace it-by any other light source, the luminosity of which-may be caused to vary in response to incoming voltage variations. r

The viewing-assembly is mounted on aver- 'tically,-movable frame 7 which is provided with azrack 8 arranged to mesh with a pinion 10. The pinion 10 is provided with conless than the radial distance between successive convolutions of the scanning-opening spiral. and it is disposed at such distance from the disk that only one opening isvinstantaneously visible thereth-rough.

In'the o eration of my improved television 7 receiver, t e disk isfirst caused to rotate at a high rate of speed, synchronism with a similar disk at a transmitting station. The

any method well known to those' skilled in the art, the observer, by looking through the viewing lens towardthe disk, sees a reproduction of the view being transmitted, If

' the instan-taneous angular position'of the revision receiver comprising a preferred ein ceiving disk differs from that of the transmitting disk, however, the picture seen by the observer will notibe properlyv framed, but will appear too high or too low in-thewiewing aperture. The reason forthis displacement, lies in the fact that the openings in p the FGCQIVlIlgdlSk are either instantaneously hi her or instantaneously lower with respect be too low, the viewing assembly is moved downward. The movements may, however,

be in the opposite directions if the viewingassembly is at the limit" of its travel just :prececling the adjustment. The movement of the assembly either upward or downward is equivalent to giving the, disk an angular movement backward or forward with respect to the direction of rotation, independently of the motor drive and, since the scanning-openings are arranged in a-spiral having two or morerevolutions, the equivalent angular ad- Vance or retardationof the diskmay be-made any amount from afew seconds of are up to and-past 3609}. V 7

If the light source isisufiiciently large, it

is not necessary to raise or lower it simul-- taneously with the viewing lens and viewing aperture, but it may remain fixed in position during the framing operation; It might also, in some cases,'be simpler to fix theentire viewing-assembly, and to raise or lower the motorand disk, the same relative amount.

I have, accordingly, provided a television receiver in Which'tl e picture mav' be simply and expeditiously framed without thenecessity of a plurality of trial and error adjust merits, After the framing has once been accomplished, it remains substantially perfect u nless the driving motors for the disks at thetransmitting and the receiving stations depart from synchronism'l I invention as applied to a television systemiof the type wherein scanning-disks are used, it is not to be restrictedto the specific apparatus illustrated. Many. modifications of,

Although I have chosen to illustrate my my invention will be apparent to those skilled in the art and it is my intention thatits scope 1 shall'be limited only insofar as is necessitated by the prior art or by the spirit of the appended claims.

I claim as myinvention: r

1. In a television receiver, ascanning device, motive means for said device, a viewing-assembly, and means for moving said viewing-assembly bodily in a radial direction with respect to said scanning means, whereby. the efiect of a change in the angular relation between said scanning device and saidmotive means is obtained and thereceived pic ture may be framed. i

2. In a television recelver, a rotatable disk provided with scanning openings disposedin a spiral having a plurality of convolutions,

a viewing-assembly, and means forymoving I said viewing-assembly radially of said disk.-

' 3. i In a television receiver, a rotatable disk provided with scanning openings disposed in a spiral having a plurality of convolutions, a viewing-assembly comprising a variable light source, a viewing aperture and a viewing lens, and means for moving said viewingassembly radially of said dis 4. In a televislon receiver, a rotatable disk provided with scanning openings disposedin a spiral having a plurality ofconvolutions, a viewing-assembly comprising a variable'light source, a viewing aperture and a viewing lens, and means for moving said viewing-assembly radially of said disk.

5. In a television receiver,a rotatable disk provided with scanning openings disposed in a spiral having a plurality of convolutions," a variable light source disposed adjacent to p said openings at one side ofsaid disk, means 40 disposed adjacent to-Vthe other side of said .disk for observing the illuminated openings, 7

and means for moving said viewing means radially ofsaid disk.

r 6. In a television receiver,-a rotatable disk provided with scanning openings disposed in a spiral having a plurality of convolutions, a variable'light source disposed adjacent to said openings at one side of said disk, viewing means comprising a frame and a lens,

' disposed adjacent to the other side of said disk for observing the illuminated openings, and means whereby said viewing means may be moved radially of said disk. 7 V v In testimony whereof, Ihave hereunto subscribed my name this 18th day of June, 1928. V '7 ROBERT L. DAVIS. 

